Solid-state imaging systems or imaging readers have been used, in both handheld and/or hands-free modes of operation, to electro-optically read targets, such as one- and two-dimensional bar code symbols to be decoded, as well as non-symbol targets or forms to be imaged. A known exemplary imaging reader includes a housing held by a user, a window supported by the housing and aimed at the target, and a scan engine or imaging module supported by the housing and having a solid-state imager (or image sensor) with a sensor array of photocells or light sensors (also known as pixels) that face forwardly toward the window, and an imaging lens assembly for capturing return light scattered and/or reflected from the target being imaged along an imaging axis through the window over an imaging field of view, and for projecting the return light onto the image sensor to initiate capture of an image of the target over a range of working distances in which the target can be read. Such an image sensor may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the imaging field of view. These electrical signals are decoded and/or processed by a programmed microprocessor or controller into information related to the target being read, e.g., decoded data indicative of a symbol target, or into a picture of a non-symbol target.
Since the user of the imaging reader cannot see exactly whether a target is located entirely within the imaging field of view of the image sensor, or know whether the target is optimally centrally located within the imaging field of view, the imaging module also typically includes an aiming light assembly for projecting a visible aiming light pattern, for example, a generally circular spot, or a cross-hairs, for placement at, or near, the center of the target, or an aiming line, or a series of generally circular spots linearly spaced apart, for placement lengthwise along the target, to assist the user in visually locating the target within the imaging field of view and, thus, advise the user in which direction the reader is to be moved in order to accurately spatially position the aiming light pattern on the target, especially prior to reading. The aiming light assembly includes at least one aiming light source, such as an aiming laser for emitting an aiming beam, an aiming lens, and a pattern shaping optical element, such as a diffractive optical element (DOE), or a refractive optical element (ROE). The focused light passing through a DOE forms multiple diverging beamlets, which project continuous lines or rows of spots arrayed in the aiming light pattern on the target to indicate the imaging field of view.
As advantageous as such known imaging readers have been, they have proven to be less than satisfactory in certain situations. For example, the aiming light assembly is typically mounted on the imaging module at a distance of a few millimeters away from the image sensor. In such event, the aiming light pattern is offset from the imaging field of view, and the offset worsens with increasing working distance. This offset problem is particularly acute when a one-dimensional image sensor that is, for example, only one pixel tall, is employed because an offset of even a few millimeters cannot be tolerated for efficient reading performance.
To counter this offset problem, it is known to steer the aiming pattern to overlap the imaging field of view by moving the aiming lens relative to the aiming laser. However, this movement is constrained, because the aiming laser has to be coaxial with an outside diameter of the aiming lens. Also, this movement to counter the offset problem may concomitantly degrade focusing of the aiming light emitted by the aiming laser. Further complicating the offset problem and the possible focusing degradation is that there is often simply not enough room to gain access to the aiming lens and/or to allow such movement. There are many space-limited applications where a miniaturized, highly compact, imaging module is desired and, in such cases, the offset problem is unsolved and just tolerated.
Accordingly, there is a need to easily spatially adjust the aiming pattern and/or to easily adjust the focusing of the aiming light, either independently or simultaneously, in a miniaturized, highly compact, imaging module for use in an imaging reader.
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The arrangement and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.